SOLVED Problems with what I think is a "ransom"virus

[Chanoleo]

I have a big problem: My portable is completely unusable. I explain.

It is a Toshiba Satellite L50D-B with OS. Windows10 and almost new.

A few days ago I switch it on as every day, but I found with surprise that I got an alarm telling me that my system was infected by a virus and for protection, Microsoft was going to close it and that I need to call a number for instructions.

As I had already heard that you should never call numbers with similar messages, I only I turned off the unit and turned it on after a few minutes. To my surprise, it began to start on but it blocked announcing me a virus. But my antivirus (Avira) and my Firewall didn’t move

I opened the "Command Promt" to see if you could understand something and I found with surprise that C: > was empty, 0 files, D: > same thing and appeared an strange X: > with the files that should be on C: >. That certainly was the reason why the system crashed.
I try to reboot the system with the Windows 10 install disc but without success. I have access to "Safe Mode" but it do not allow me to format C: / or D: or the mysterious X: /
Can someone help me telling me which procedure to take?

Any help please? Thanks in advance

 

[Trouble]

I have access to "Safe Mode"

Sounds to me like you have something that has compromised your user profile and is running at normal startup that is not running in Safe Mode.
You need to use Safe Mode and the following three free products to scan you system to see if you can clean it up.
ADWcleaner from here http://www.bleepingcomputer.com/download/adwcleaner/dl/125/
JRT (Junkware Removal Tool) from here http://www.bleepingcomputer.com/download/junkware-removal-tool/dl/131/
Malwarebytes from here http://www.malwarebytes.org/mwb-download/confirm/
You may need to use a second computer to download those programs to a thumbdrive and run them from there, if your computer will not boot into Safe Mode with Networking or you want to avoid any networking / internet connectivity until the system has been cleaned.

C: > was empty, 0 files, D: > same thing and appeared an strange X: > with the files that should be on C:

When you boot from external media such as the installation media (command prompt), your drives and partitions will not be enumerated normally C: will not be the normal C: and X: is the Windows RE on the installation media and why it looks similar to your C: